1. Field of the Invention
The present invention relates to an ink jet recording apparatus and a method for operating such apparatus. More particularly, the invention relates to an ink jet recording apparatus that performs the recovery operation while in a recording operation, and a method for operating such apparatus.
2. Related Background Art
A recording apparatus, which is provided with the functions of a printer, a copying machine, a facsimile equipment, and the like, or a recording apparatus used as an output device for a complex type electronic equipment including a computer and a word-processor, or for a work station, is structured to record images on a paper sheet, a thin plastic plate, or some other recording material (recording medium) in accordance with image information. These recording apparatuses are divided into an ink jet type, a wire-dot type, a thermic type, a laser beam type, among others, depending on the recording method that each of them adopts for its recording operation.
Generally, in a serial type recording apparatus that scans in the direction substantially perpendicular to the feeding direction of a recording material (sub-scanning direction), a carriage having a recording head mounted on it serving as recording means travels on a recording material after the recording material has been set at a given recording position. In this way, images are recorded on the recording material in the main scanning direction.
Then, when a one-line portion is recorded, a sheet feed (pitch feed) for a given amount is performed. After that, recording is again executed in the main scanning direction to record images on the next line on the recording material, which is now at a standstill.
The operation described above is repeated to perform the entire recording on a recording material.
Of those recording apparatuses, an ink jet type recording apparatus (an ink jet recording apparatus) that records on a recording material by discharging ink from the recording head serving as recording means has the following advantages:
(1) Recording means can be easily formed compactly. PA1 (2) A highly precise images can be recorded at high speeds. PA1 (3) Recording is possible with respect to an ordinary paper sheet without providing any particular treatment for such paper sheet. PA1 (4) Running costs are low. PA1 (5) Being non-impact type, the apparatus makes lesser amount of noises. PA1 (6) Color images can be recorded easily by use of multiple color ink. PA1 a carriage to mount on it a recording head provided with discharge ports to discharge ink, and to move the head; PA1 a cap to be in contact with the recording head to cover the discharge ports; PA1 a pump to suck at the discharge ports through the cap when the cap covers the discharge ports; and PA1 control means for enabling the recording head to wait for a given period of time in a position for the recording head to face the cap before the carriage begins to carry the recording head subsequent to the suction of the pump and the separation of the recording head and the cap. PA1 sucking at discharge ports through a cap when the cap covers the discharge ports of a recording head; PA1 causing the recording head and the cap to part from each other; PA1 enabling the recording head to wait for a given period of time in a position to face the cap; and PA1 moving the recording head by use of a carriage that travels with the recording head being mounted thereon.
Also, it is ease to record at a higher speed by use of the recording apparatus of line type having a line type recording head provided with a plurality of discharge ports arranged in the feeding direction (sub-scanning direction) of a recording material.
Further, with the recording apparatus wherein ink is discharged from the recording head downward almost in the vertical direction, no gravitation causes ink to curve when its flying is initiated. Therefore, it is possible to make the shooting accuracy of ink excellent with respect to a recording material, and to perform printing more precisely.
Of the ink jet recording apparatuses described above, the one having the ink jet type recording means (recording head) that discharges ink by the utilization of thermal energy can be produced easily through semiconductor fabrication processes, such as etching, deposition, sputtering, and so forth. This enables the film formation of electrothermal transducing elements, electrodes, walls of liquid paths, ceiling plate, and others on a base board, hence making it possible to provide a highly densified arrangement of liquid paths (discharge port arrangement), and to implement making recording means more compactly. Also, it becomes easier to provide a fully multiple recording means and assemble it in a higher density by the utilization of the well advanced IC technologies and micro-machining techniques, which facilitates the elongation and surfacing (two-dimensional arrangement) of recording means.
Nevertheless, in an ink jet recording apparatus of the kind, defective discharges (including disabled discharges) may take place in some cases if discharge ports are clogged by paper particles, dust particles, or some other foreign substances adhering to the ink discharge ports of the recording head or if ink is dried in the discharging portion to make it more viscous or cause it to be fixed thereto. Also, when a new ink cartridge or a new head cartridge is used for the first time, the condition of the ink paths from the discharge ports to the ink tank is not exactly regulated at all times. Therefore, in order to prevent the clogging or to keep the ink paths normal, there are provided cleaning means for removing foreign substances adhering to the ink discharge ports (discharge port formation surface) of a recording head or recovering means for normalizing the discharge ports and ink paths of a recording head.
As cleaning means, a mechanism is adopted to wipe off and clean the discharge port formation surface of a recording head mainly by use of a flexible wiper (wiping member). Also, as recovering means, a recovery device is adopted to cover the ink discharge ports of a recording head mainly by means of a cap when recording is at rest, and at the same time, to suck ink from the ink discharge ports by suction means, such as a pump, through the cap, thus normalizing the ink discharge ports and ink paths.
FIG. 4 is a view showing one structural example of an ink jet recording apparatus of serial type in accordance with the related background art.
As shown in FIG. 4, an apparatus exemplified here comprises at least a carrier roller 108, which is connected to a recording sheet carrier motor (not shown) through a gear train and others of a driving force transmission mechanism 109, and which carries a recording sheet 115 serving as a recording material; a sheet exhaust roller 112 connected to the carrier roller 108 through a driving force transmission gear train 113, while being biased to a spur 114 by means of a biasing member (not shown); a pinch roller 110 rotatively supported on a pinch roller holder 111, which is biased to the carrier roller 108 by means of a biasing member (not shown); a recording head 106 integrally formed with an ink tank, the ink discharge ports of which are arranged downward, serving as recording means for recording on the recording sheet 115; a carriage 101 having the recording head 106 mounted thereon; a guide shaft 102 supporting the carriage 101 slidably in the direction orthogonal to the carrying direction of the recording sheet 115, and also, in the direction parallel to the surface of the recording sheet 115 (in the direction indicated by arrows A in FIG. 4); a carriage driving belt 105 to enable the carriage 101 to reciprocate in the straight-line direction; and a carriage driving motor 103 and a pulley 104. Also, the recording head 106 is connected electrically to a control board (not shown) through a flexible board 107.
Further, outside the recording area, there are provided a wiper 120 structured and interlocked with the movement of the carriage 101 to be able to contact with or part from the ink discharge ports of the recording head 106 in order to clean the recording head 106; a pump 119 to execute the recovery operation of the ink discharge ports in order to keep the ink discharge performance of the recording head in normal condition; and a cap 118 conductively connected to a waste ink tank (not shown) through the pump 119.
Now, the description will be given below as to the printing operation of an ink jet recording apparatus structured as described above:
At first, when a recording sheet 115 is inserted into a recording sheet inlet aperture (not shown) formed by guide members 116 and 117, the recording sheet 115 is pinched by the carrier roller 108 and the pinch roller 110. By the rotation of the carrier roller 108, the recording sheet is carried over to the recording position facing the ink discharge ports of the recording head 106.
Then, the carriage driving motor 103 is driven to rotate the carriage driving belt 105. The carriage 101 reciprocates along the guide shaft 102 in the straight-line direction. At the same time, in response to recording signals, ink is discharged from the recording head 106 mounted on the carriage 101, thus recording the contents to be recorded on the recording sheet 115.
When a one-line portion is recorded, the carrier roller again rotates to carry the recording sheet 115 to the next recording position, where the carriage 101 reciprocates to record the next line.
With the repetition of the operation described above, recording is made on the recording sheet 115.
During the operation described above, the cleaning operation is executed to remove foreign substances adhering to the ink discharge ports of the recording head 106, and the recovery operation is performed for the recording head to implement the normalization of the discharge ports and ink paths.
Now, in accordance with this example, the description will be given below as to the cleaning operation and recovery operation of the recording head.
FIG. 5 is a flowchart showing the flow of cleaning and recovery operations for the recording head of the ink jet recording apparatus shown in FIG. 4.
Usually, when recording is not in operation nor any capping and recovering operations are performed for the recording head 106 of an ink jet recording apparatus, the cap 118 is in contact with the ink discharge portions of the recording head 106 in a cap closed condition (step S201).
When the cleaning and recovery operations are needed for the recording head 106, the cap 118 is driven to part from the ink discharge ports of the recording head 106, thus being in a cap open condition (step S202).
Then, the wiper 120 moves to a position where it can abut upon the ink discharge ports of the recording head 16. While the wiper 120 and the ink discharge ports are in a contact state, the carriage 101 reciprocates in a portion within a given range in the main scanning direction in order to clean the ink discharge ports by means of wiping (step S203). Here, it is assumed that the range for the carriage to travel is a minimum dimension required for the wiper 120 to wipe the ink discharge ports.
When the cleaning of the ink discharge ports by means of wiping is finished, the cap 118 is in contact with the ink discharge ports, thus being in a cap closed condition (step S204).
In the cap closed condition, the ink that has become unsuitable for printing, which is retained in the ink discharge ports, are sucked by the pump 119 compulsorily through the cap 118 (step S205).
When the ink suction is completed, the cap 118 is driven to part from the ink discharge ports, thus again being in the cap open condition (step S206).
At the same time that the cap is in the open condition, the carriage 101 moves to a retracted position where the cap 118 is not allowed to face the ink discharge ports (step S207).
After the carriage 101 has moved, the ink sucked from the ink discharge ports and retained in the cap 118 in the step S205 is sucked and exhausted to an waste ink tank (step S208).
After that, by the same operation as in the step S203 the ink discharge ports are again cleaned by means of wiping (step S209).
When the cleaning of the ink discharge ports by means of wiping is finished, the cap 118 abuts upon the ink discharge ports, thus being in the cap closed condition (step S210).
On the other hand, there are various demands on the kinds of recording materials (recording sheets). In recent years, there have been in demand those having perforations or a rolled continuous paper sheet for use of a hanging screen, besides an ordinary recording sheet material. As a result, it has become necessary to perform the recovery operation in a state that a recording sheet is still set at a recording apparatus.
Now, the ink jet recording apparatus described above is structured to compulsorily suck, in the cap closed condition, the ink that has become unsuitable for printing but still remains in the ink discharge ports, and then, in the cap open condition, the carriage moves to the retracted position where the ink discharge ports are not allowed to face the cap in order to suck the ink, which is retained in the cap.
FIG. 6 is a perspective view showing the ink jet recording apparatus represented in FIG. 4, observed in the direction indicated by an arrow D in FIG. 4, immediately after the cap has been open subsequent to the ink suction.
As shown in FIG. 6, the ink 121, which is sucked into the cap 118 from the ink discharge ports 106a, is sometimes caused to remain in a state of being connected between the cap 118 and the ink discharge port 106a due to the relationship between the allowable capacity of the cap 118 to hold ink and the amount of ink being retained in the cap 118, and the relationship between the distance from cap 118 to the ink discharge ports 106a and the viscosity of ink as well.
On the other hand, the retracting position, which the carriage 101 should move to the retracting position, which is arranged on the passage area of the recording sheet 115 so that the main body of the recording apparatus can be made compact. Therefore, when the carriage 101 moves, it should travel on the passage area of the recording sheet 115.
As a result, there is a problem that a recording sheet 115 is stained if the recording sheet 115 is present on the passage area arranged for it, while the carriage 10 moves in such a state that ink 121 is still connected between the cap 118 and the ink discharge port 106a, because the ink, which trails from the recording head 106, is liable to drop onto the recording sheet 115.